Reduction of oxygen content in laser powder bed fusion process atmosphere – Effects on stochastic defect formation and mechanical properties
Journal article, 2024

Stochastic defects in materials manufactured via laser powder bed fusion (LPBF) can severely compromise mechanical performance and are challenging to predict and detect, thus motivating the development of defect mitigation strategies. Particle oxidation is a factor well-known to generate defects by disturbing melt pool dynamics. If the particles are spatters, additional disturbances increase the likelihood of defect formation. In this study, restricting oxygen content in the process atmosphere to 50 ppm is investigated to minimize stochastic spatter-induced defects and improve the mechanical properties of Hastelloy X. Specimens were manufactured under this condition at two nominal layer thicknesses, analyzed for internal defects, and mechanically tested. Contrary to expectations, reducing the oxygen content did not prevent spatter-induced defect formation; rather, it could exacerbate the formation of more numerous and larger defects. Nevertheless, this tighter control of the process atmosphere led to significant microstructural refinement, which, when combined with sparse defects, resulted in improved fatigue performance. Despite the inherent ductility of Hastelloy X, the presence of abundant defects significantly larger than the microstructural characteristic size proved detrimental to fatigue performance. Notably, the occurrence of defects exhibited considerable variation across the build area, contributing to scatter in fatigue data. However, quantitative analysis of in-situ monitoring data enabled prediction of variability in defect content and mechanical performance.

Defect mitigation

Defect detection

In-situ monitoring

Spatter

Oxidation

Fatigue

Author

Claudia de Andrade Schwerz

Chalmers, Industrial and Materials Science, Materials and manufacture

JJ Moverare

Linköping University

Alain Küng

RISE Research Institutes of Sweden

Benjamin Bircher

RISE Research Institutes of Sweden

Dmitri Riabov

Höganäs

Chalmers, Industrial and Materials Science, Materials and manufacture

Lars Nyborg

Chalmers, Industrial and Materials Science, Materials and manufacture

Journal of Materials Research and Technology

22387854 (ISSN) 22140697 (eISSN)

Vol. 30 4667-4681

Quality control an dynamic response by on-line monitoring of additive manufacturing

VINNOVA (2022-02549), 2022-11-08 -- 2025-11-07.

Additive Manufacturing using Metal Pilot Line (MANUELA)

European Commission (EC) (EC/H2020/820774), 2018-10-01 -- 2022-09-30.

Subject Categories

Materials Chemistry

Metallurgy and Metallic Materials

DOI

10.1016/j.jmrt.2024.04.177

More information

Latest update

6/24/2024